i used to have 2 in cloth. i just got a messenger bag at target for about $15 i think. it holds 3 aios, a change of clothes for my 16 month old. It also holds 3 pairs of underweare and 2 changes of clothes for my 4t size 3 year old with much more room!
I have a Kecci Shanghai Mommybag which is a nice size for cloth diapering but not necessarily the most durable bag out there. I generally put enough in that bag for one change, then keep another bag in the car to "refill" the bag with- I call it my auxillary diaper bag.